1. Field of the Invention
The present invention relates to warning light systems in the form of a light bar intended primarily for installation on land and marine vehicles and particularly to a light bar assembly having an integrated warning light and lens support structure.
2. Description of the Related Art
Warning light assemblies in the form of light bars mounted on emergency vehicles are well known in the art. Such light bars typically comprise an elongated base to which warning lights and lenses are mounted. The light bar may also include power supplies and control circuitry to provide a self-contained light bar assembly. The light bar exterior typically includes multiple lenses that re-direct and/or color light from the warning light units mounted inside. A rigid base of metal or plastic provides mounting points for attaching the light bar to the emergency vehicle and for supporting the warning light units, lenses and other light bar components.
It is known to provide the base of a light bar in the form of an extrusion. A relatively complex, elongated base of high-strength can be produced efficiently by extrusion from aluminum, plastic, or the like. U.S. Pat. No. 4,620,268, assigned to the assignee of the present invention, is illustrative of a light bar utilizing an extruded support structure. It should be noted that in the '268 patent, lens portions are slidably received into outward-facing “locking grooves” defined by the extrusion. While such a lens/support structure relationship allows for efficient and flexible manufacture, the sliding lens and channel relationship is difficult to seal against penetration by water. Specifically, water penetrates the lens/channel joint by capillary action and under pressure from wind and water present in the emergency vehicle environment. Configuring the lens edges to be received more tightly in the locking grooves may cause the lens portions to bind during assembly.
Weather resistance, in particular resistance to penetration by water, is an important feature for a light bar intended for installation on land and marine emergency vehicles. Such vehicles are typically exposed to extremes of heat and cold as well as water in the form of ocean spray, rain, sleet, snow and ice. Penetration of water or moisture into a light bar can have adverse effects ranging from fogging the lenses to corroding metal parts to destruction of electronic components.
A light bar typically includes lens portions of different colors and alternative light-refracting characteristics. Assembling the light-transmissive cover of a light bar from discrete lens portions allows production of a light bar in which the pattern of warning light units and colors may be changed to suit customer requirements. Manufacture of a one-piece light-transmissive cover including clear and colored portions with different light refracting patterns is impractical. Further, discrete lens portions allow access to internal components for service of a light bar by permitting removal and/or replacement of lens portions as opposed to the entire light-transmissive cover of the light bar.
A light bar with a light-transmissive cover assembled from discrete lens portions complicates the problem of providing a weather-resistant enclosure. The '268 patent discloses gasket dividers compressed between longitudinal edges of the lens portions. Light bar end caps engage the extruded support structure to hold the lens portions and gaskets in a sealed relationship. The gasket material seals lens edges to dividers when the lens portions are compressed along the length of the light bar. While this approach improves weather resistance of the junction between lens portions, it fails to address weather resistance of the joint between the longitudinally received lens portions and an extruded base. The sliding relationship between the lens portions and the extruded base make inclusion of gasket or other sealing material in the joint problematic.
A further drawback to the light bar assembly typified by the '268 patent is that access to internal components in the middle of the light bar requires disassembly of all lens portions between one end of the light bar and the position of the component in need of service. Other manufacturers have taken the approach of breaking the light-emitting portion of a light bar into discrete units, each unit individually sealed to an elongated substructure. This approach lacks the flexibility of light bar fabrication provided by an elongated support structure with a light-transmissive cover that together define a substantially uninterrupted internal space. Such an internal space may be filled with a variety of power supplies, control circuits and warning light modules. As long as the components are arranged to fit within the space defined by the base and light-transmissive cover, the manufacturer is free to configure the light bar as required by a particular standard or customer specification.
There is a need in the art for a light bar with a light-transmissive cover in the form of a modular lens system where the connections between discrete lens portions and the junction of the light-transmissive cover with an elongated light bar base structure demonstrate improved weather resistance. Such a modular lens system will ideally enhance the efficiency of manufacture, assembly and service of the light bar.